Open-end spinning of yarn is becoming increasingly commercially popular because of a number of inherent advantages of open-end spinning over conventional ring spinning. Some of the advantages of open-end spinning over ring spinning are: yarn formation and winding are not interdependent, allowing for removal of full packages while the machine is running; package size is theoretically unlimited; power consumption increases little with package weight; and package shape is suitable for most of the succeeding operations so that rewinding is eliminated. Additional advantages are the appearance, processability, and economy of the open-end yarns, and generally improved performance of end-products made with open-end yarns.
While it is desirable to be able to produce open-end novelty yarns (particularly open-end slub yarns), there have been a large number of practical problems associated with conventional techniques and proposals for making open-end novelty yarns. As a result, most novelty (particularly slub) yarns now produced are ring spun. Present conventional and proposed methods for formation of slubbed open-end yarns include applying the slubs to the sliver before it is fed to the spinner; rapidly increasing or decreasing the feeding rate of the sliver; varying the withdrawal speed of the yarn from the spinner (U.S. Pat. No. 4,144,730); and forming the slubs exteriorly of the open-end spinning operation and then adding the slubs in a separate path to a point just before the yarn spinning device.
All conventional and proposed techniques for making open-end novelty yarns have disadvantages associated therewith. For instance slubs added to the sliver require extra processing, they have a tendency to become lost as "trash" during the fiber separating stage (e.g. carding and combing), and they interfere with the combing of the fibers. Slubs made by controlling the feeding and withdrawal speeds of the sliver and yarn respectively do not allow production of a wide variety of different types of novelty yarn, and the slubs produced have a character that is undesirable for many operations. The feeding of slubs in a different path exterior of the open-ended spinning device requires the construction of an entirely separate system which can be expensive, takes up valuable room, and does not lend itself to ready adaptation to pre-existing equipment.
According to the method and apparatus of the present invention, most of the drawbacks associated with conventional and proposed techniques for open-end novelty yarns have been overcome, and it is possible to produce novelty yarns (particularly slub yarns) having most of the desirable features of conventional ring-spun slub yarns. The method is subject to wide applicability and ready control to produce a wide variety of different novelty effects, and the apparatus according to the present invention is basically simple and is believed to be adaptable for use on almost any type of conventional open-end spinning equipment, and in fact can be retrofit onto most conventional open-end spinning equipment.
According to one aspect of the method of the present invention the open-end spinning of a novelty yarn is practiced utilizing an open-end spinning apparatus having a fiber separating device, a twisting device, and a fiber transport section interconnecting the separating and twisting devices. The method comprises the steps of effecting controlled formation of effects (preferably slubs) in the fiber transport section, and intermittently passing these effects to the twisting device. The effect formation step is preferably accomplished by introducing a physical structure, such as an elongated needle, into the fiber stream in the transport section to cause fiber collection thereon. Preferably the needle--or a plurality of needles--is inserted into and withdrawn from the fiber stream in the transport section on a pseudo-random basis, producing pseudo-random slubs and the desired configuration of slub yarn.
The invention is useful for making a wide variety of novelty yarns, which in general includes any yarn having unusual or special effects such as nubs, neps, lumps, slubs, or the like. However the invention is primarily suitable to the production of slub yarns. Slub yarns are a particular species of novelty yarn with soft, thick, unevenly twisted lengths which alternate with essentially normalsized places in the yarn. Slub yarns provide a very definite and readily discernible texture effect in the products into which they are made, the degree of course being dependent upon the frequency and size of the slubs, providing well defined, relatively large surface manifestations in the products produced with the yarn.
According to another aspect of the present invention a method of open-end spinning a novelty yarn from a sliver utilizing a fiber separating device and a twisting device is provided. The method consists essentially of the following steps: (a) Feeding the sliver to the fiber separating device to form distinct fibers. (b) Air transporting the distinct fibers in a fiber flow in a predetermined general path to the twisting device. (c) Effecting controlled formation of effects during air transport of the distinct fibers in said general path. (d) Intermittently passing the formed effects to the twisting device. (e) Twisting the fibers fed to the twisting device, including any effects passed thereto, into a continuous strand of novelty yarn; and (f) Taking up the novelty yarn continuous strand. Step (c) is preferably accomplished by the pseudo-random insertion and withdrawal of one or more needles into and out of the fiber flow path, and the formed effects are preferably passed to the twisting device pseudo-randomly, responsive to the control of the insertion into and withdrawal from the fiber flow path of the needles.
The apparatus for practicing the present invention comprises a spinning device including a fiber separating device, a twisting device, and a fiber transport section disposed between the separating and twisting devices. The fiber separating device may be of any conventional type such as a conventional opening roll, and the twisting device may also be of any conventional type such as a rotor. According to the present invention means for effecting controlled formation of effects in the fiber transport section and for intermittently passing the formed effects to the twisting device are provided. The particular means preferably includes one or more needles and a means associated with each needle for intermittently (e.g. pseudo-randomly) inserting the needle into and withdrawing it from the fiber transport section (such as through the wall of the fiber transport tube).
By practicing the method according to the present invention a novelty yarn in general, and a slub yarn in particular, is produced that has the desired variety and many characteristics of conventional ring spun slub yarns, and the invention may be practiced in a simple, inexpensive, and effective manner.
It is the primary object of the present invention to provide a simple and practical method and apparatus for producing open-end novelty (particularly slub) yarns, and the yarn so produced. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.